Madrid and Barcelona Museum tickets

I don't know about senior tickets at specific museums, but in Spain they can offer considerable savings when available. In some cases they may be limited to locals or EU citizens. Sometimes there's a little "i" in a circle beside the concessionary entry fee; that's a clickable link where you should find the rules for qualifying.

I don't think you'll encounter a ticket line of any consequence at either the Thyssen or the Reina Sofia--though I guess there's a slight possibility you'll arrive right behind a tour group and have to wait while 20 tickets are printed out. In 2016 I just didn't observe significant ticket lines anywhere in Madrid. I'm aware more people are traveling this year, and I did not go to the archaeological museum.

In Barcelona you should buy tickets ahead of time for any of these places you want to go, because they have dreadful ticket lines and the potential to sell out:

La Sagrada Familia
Parc Guell
Casa Mila/La Pedrera
Casa Batllo
Picasso Museum

In addition, the English-language tours at the Palau de la Musica Catalana can fill up, and they don't run constantly.

I think Madrid has an art-museum pass, but I don't know how its price aligns with senior entry charges (or whether Americans can buy senior tickets).

I don't think Barcelona has a useful, money-saving sightseeing pass.

In 2017 there was a 3 museum Prado, Theissen, Sofia combo. You stood in one line as yes, you needed to pick up in person. (Theissen was typically the shortest line). But as you jave already ordered Prado, then it is a moot point. Reina Sofia has free hours, Sunday I think, and if Guernica is the main draw, then thst could do. Yes, those galleries will be busy, but other areas may be almost empty. Also, any temporary exhibits with extra fees are not covered by the bundled tickets so there coild be line ups regardless. Thyssen often has an extra draw. When I was there it was Toulouse Latrec.

Thank you acraven, you have been very helpful with my various questions on this forum, and mariaF for your informative response.
I had looked into art museums passes and found that, while the Madrid Art Walk pass covering the Prado, Reina Sofia, and Thyssen, seems to be a good deal at 32 Euro, vs 15 for Prado, 12 for Reina Sofia, and 13 for Thyssen, since the Prado offers seniors (65 and over) discounted tickets @ 7.50 Euro, and Thyssen offer seniors 9 Euro tickets, the Art walk ticket didn't make sense for us seniors.
Even adding full price for Reina Sofia 12 Euro), as seniors it costs us a total of 28.50 Euro each for the 3 , versus the Art Walk ticket cost of 32 Euro.
I wrote directly to Reina Sofia, and it seems that as senors, one can get free entry, but you have to get your tix at the museum in person, and depend on availability. To me it isn't worth the risk of missing out on Guernica and more just o save a few Euro

Did you see the free slots for Reina? https://www.museoreinasofia.es/en/visit/opening-hours-and-ticket-prices
I would do one of those 7pm slots and not worry about missing out on Guernica.
I may be one of the few, but I was less impressed with it than expected. Maybe it is because you enter through a room with photographs of the reality at the time. I didn't know that and was not prepared. As there was a slow down to get to the Picasso, it was difficult to avoid the photos and I was already in an emotional state so an artistic depiction was underwhelming to me.
If you are a sensitive soul, keep tissues and su glasses handy.

For the Reina Sofía, it appears there is free admission for those over 65. You will need to show a passport when you pick up the ticket at the ticket office. There are also free admission times, Mon and Wed-Sat 7-9pm and Sunday between 12:30-2:30pm if you’re under 65. If you’re only going to see certain exhibits, e.g., Guernica, two hours is more than enough time. The Prado has free hours too.

From the Reina Sofía website:

“Tickets are collected at the Museo ticket offices upon submitting the official accreditation document that is valid for each case. This must clearly show the expiry date.

All visitors that are able to accredit this condition can benefit, regardless of their nationality.

Should documents not include a photograph, an ID card or passport must be shown.

Children and youth under the age of 18
People over the age of 65
…”

Two times I visited the Reina Sofía it was during the free admission times. It took maybe twenty minutes to get in, but we still had plenty of time to see everything else.

The Prado’s free hours: Visit from Monday to Saturday from 6:00 p.m. to 8:00 p.m. and Sunday and holidays from 5:00 p.m. to 7:00 p.m.

I'd agree that the free entry to Reina Sofía is sufficient to see Guernica (which made me weep both times I've seen it). The rest of the collection there is unremarkable.

The Thyssen's collection is impressive but horribly organized. The museum is a curatorial embarrassment.

I'm a huge fan of Madrid's minor museums—there are masterpieces tucked into jewel boxes all around the city.

To all, and particularly acraven, who is a veritable font of helpful info.
Just wanted to share our recent (March 15-24, 2023 )experience with museum and related tickets for Madrid and Barcelona
We purchased all our tickets in advance from each museum or palace’s official website.
Most do offer senior or “pensioner” reduced price tickets for those 65 or older. Sometimes the language on the website wasn’t terribly clear whether one has to be a EU citizen to qualify, or just be 65 or older. Where offered, we chose the senior tickets, figuring if we didn’t meet EU requirements, we could always pay the difference on arrival at each museum or palace.
As it turned out, all our senior tickets were honored with no problem whatsoever. Personnel at The Prado did ask to see our passport for proof of age, at Sagrada Familia we were waved through, with the “explanation” that ID was not needed that particular day.
Senior tickets were also accepted matter of factly at Parc Guell, the Picasso Museum, at Madrid’s Royal Palace, and at the Thyssen Museum.
Senior ticket are also honored on the City Tour Hop On, Hop Off buses in both Madrid and Barcelona, with no one ever asking for proof of age.
The savings add up, and make purchasing a multi museum card inadvisable for those of us 65 or older.